Coronary Computed Tomography Angiography (CCTA)

CCTA is used instead of nuclear SPECT scan which has a 40% false-positive and 65% false-negative, and instead of cardiac catheterization which is invasive and risky. Both of these test also have higher radiation exposure than CCTA.

Introduction

Computed tomography, commonly known as a CT scan, combines multiple X-ray images with the aid of a computer to produce cross-sectional views of the body. CCTA is a heart-imaging test that uses CT technology with intravenous (IV) contrast (dye) to visualize the heart anatomy, coronary circulation, and great vessels (which includes the aorta, pulmonary veins, and arteries).

High resolution images acquired during diastole significantly reduces motion artifact seen with conventional CT which may obscure underlying pathology.

Benefits of CCTA

  • Non-invasive: Compared to cardiac catheterization, CCTA only requires an IV, not femoral access or the passage of wires and catheters into the aorta and coronary arteries, thereby eliminating the risk of iatrogenic vascular injury, stroke, and myocardial infarction.
  • Capable of finding dangerous plaques that may lead to heart attacks.
  • Helps to isolate stenotic plaque that leads to 25% of heart attacks and reduces blood flow and causes angina.
  • Helps locate vulnerable non-stenotic plaque that does not cause angina or limit blood flow but causes 75% of heart attacks. (Plaques with thin fibrous caps, high lipid content, napkin ring like appearance of plaque which are frequently mixed with flecks of calcium with the lipid.
  • Less contrast volume: CCTA uses, on average, 50% less contrast than cardiac catheterization, which reduces the likelihood of nephrotoxicity.
  • Fast: A CCTA exam can be performed in roughly ten minutes from start to finish.
  • High sensitivity: CCTA has both high spatial and temporal resolution which allows for the accurate detection of both calcified and non-calcified (“soft”) atherosclerotic plaques. National statistics indicate that approximately 2 out of every 3 patients who undergo cardiac catheterization do not have disease requiring intervention and the negative predictive value is 99.9%. The high negative predictive value of CCTA allows more efficient triage and resource allocation and minimizes unnecessary procedures.
  • Less radiation than the dose acquired during cardiac catheterization.
  • Plaquogram: Proprietary hardware and software to image one plaque and follow it as a marker for the radiation exposure of a tenth of a chest x-ray.
CT-Myocardial Perfusion Imaging

Potential Disadvantages

  • Radiation dose: The typical radiation dose for CCTA is 3 mSv, which is the equivalent exposure to natural background radiation over one year period. This is much less than that of a nuclear stress test (dose range of 12-25 mSv). Advances in CT technology continue to decrease patient radiation exposure through faster scan times and dose-modulation techniques.
  • New advances with model based iterative reconstruction (MBIR, SAFIRE, or iMR depending on vendor) allowing testing with the level of radiation exposure the same as a routine chest x-ray.

Preparing for the CCTA

  • No caffeine or decaf for 12 hours before the test
  • May have to take Toprol-XL (Metoprolol) 2 days before test and day of test
  • No food or drink 3 hours prior to test